Occupational exposure to metals and impact on dementia incidence

Abstract

Objective: Determine the association between occupational exposure to copper or aluminum and incidence of all-cause dementia and Alzheimer’s disease (AD). Method: Leveraging data from the Adult Changes in Thought (ACT) study, we analyzed the association of occupational exposures to copper or aluminum with exposure quantification through a JEM (CANJEM) and incidence of dementia and AD for 4,354 participants. Exposure groups were divided into three categories: low, medium, and high, and compared to an unexposed reference group. Data collection occurred between February 1994 through June 2015. Results: During a median follow up time of 6.4 years, the adjusted hazard ratio (HR) for low, medium, and high copper exposure groups was 1.02 (95% CI: 0.88-1.19), 0.96 (95% CI: 0.79-1.16), and 1.05 (95% CI: 0.86-1.28) for all-cause dementia, and 1.08 (95% CI: 0.91-1.28), 1.06 (95% CI: 0.86-1.30), 1.05 (95% CI: 0.84-1.31) for AD, respectively. The adjusted HR for low, medium, and high aluminum groups was 1.07 (95% CI: 0.92-1.24), 1.15 (95% CI: 0.95-1.38), 1.12 (95% CI: 0.93-1.35) for all-cause dementia, and 1.05 (95% CI: 0.88-1.24), 1.17 (95% CI: 0.95-1.43), 1.15 (95% CI:0.93-1.42) for AD, respectively. Conclusion: Our results found little evidence that copper or aluminum increase the risk of dementia. However, the results did have wide confidence intervals with more weight above one. This study suffered from the use of a population base cohort that was older at time of entry, which could have resulted in elimination of dementia cases with an onset at younger ages This could have resulted in cases associated to early occupational exposures being excluded in this study.